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PUBLIC HEALTH ASSESSMENT

FORT WAINWRIGHT
FORT WAINWRIGHT, FAIRBANKS NORTH STAR BOROUGH, ALASKA


IV. EVALUATION OF EXPOSURE PATHWAYS

IV.A. Introduction

IV.A.1. Identifying Exposure

ATSDR's public health assessments are exposure (or contact) driven. While many chemical contaminants disposed or released into the environment have the potential to cause adverse health effects, health effects only result after a sufficient amount of exposure to the contaminant occurs. A release does not always result in exposure. People can only be exposed to a contaminant if they come into contact with that contaminant. Exposure can occur by breathing, eating, or drinking a substance containing the contaminant or by skin contact with a substance containing the contaminant.

ATSDR evaluates site conditions to determine if people could have been (a past scenario), are (a current scenario), or could be (a future scenario) exposed to site-related contaminants. When evaluating exposure pathways, ATSDR identifies whether exposure to contaminated media (i.e., soil, water, air, waste, or biota) has occurred, is occurring, or could occur through ingestion, dermal (skin) contact, or inhalation. ATSDR also identifies an exposure pathway as either completed or potential, or eliminates the pathway from further evaluation. Completed exposure pathways exist if all elements of a human exposure are present. (See "Exposure Pathway" in Appendix B for a description of the elements of a completed exposure pathway.) A potential pathway is one that ATSDR cannot rule out, because one or more of the pathway elements can not be definitely proved or disproved. A pathway is eliminated if one or more of the elements is definitely absent.

If exposure was, is, or could be possible, ATSDR considers whether contamination is present at levels that might affect public health. Contaminants are selected for further evaluation by comparing them with health-based CVs. (See the description of CVs in Section III.C. of this public health assessment.) Some of the CVs used include ATSDR-established environmental media evaluation guides (EMEGs), reference dose media evaluation guides (RMEGs), and cancer risk evaluation guides (CREGs) and the maximum contaminant levels (MCLs) established by EPA. MCLs are enforceable drinking water regulations developed to protect public health. CREGs, EMEGs, and RMEGs are nonenforceable, health-based CVs developed by ATSDR for screening environmental contamination for further evaluation. (See Appendix C for a description of the CVs.)

More information about the ATSDR evaluation process can be found in ATSDR's Public Health Assessment Guidance Manual at http://www.atsdr.cdc.gov/HAC/HAGM/ or by contacting ATSDR at 1-888-42ATSDR.

IV.A.2. Exposure and Health Effects

Exposure does not always result in harmful health effects. The type and severity of health effects that occur in an individual from contact with a contaminant depend on the exposure concentration (how much), the frequency and/or duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once exposure occurs, the individual characteristics, such as age, sex, nutritional status, genetics, lifestyle, and health status, of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. Together, these factors and characteristics determine the health effects that might occur as a result of exposure to a contaminant in the environment.

Considerable uncertainty exists about the true level of exposure to environmental contamination because of a lack of data. The exact frequency and duration of exposure or the exact contaminant concentration level are not known. To account for the uncertainty and to be protective of public health, ATSDR scientists typically use worst-case exposure-level estimates as the basis for determining whether or not adverse health effects are possible. These estimated exposure levels are usually much higher than the actual exposure levels of individuals at a site. If exposure levels indicate that adverse health effects are possible, ATSDR performs a more detailed review of the exposure and a review of information from the scientific literature on toxicology and epidemiology about the health effects of exposure to the specific hazardous substances involved. Figure 3 provides an overview of the ATSDR exposure evaluation process.

IV.A.3. Possible Exposure Situations at Fort Wainwright

ATSDR reviewed data for Fort Wainwrights's 37 PSC sites in the 5 OUs and other available (though limited) information for surface water, air, and the previously identified physical hazards to determine if they are associated with past, current, or future public health hazards. (Table 3 provides a description of each site and a brief summary of the ATSDR evaluation.) ATSDR assessed the level of contamination present or the degree of physical hazard, the extent to which individuals come into contact with the contamination or hazard, and whether or not this contact would result in a public health hazard. The review indicated that most sites at Fort Wainwright are not associated with any known public health hazards because (1) no site-related contaminants are present, (2) contaminant concentrations detected are too low to pose a health hazard, or (3) exposure to the general public has been prevented.

From this review, however, ATSDR identified several exposure situations at Fort Wainwright for further evaluation. Exposure situations considered in this public health assessment include:

Completed or potential past exposure to contaminants in

  • Groundwater via drinking water used by a nearby church,

  • Air released from Fort Wainwright's coal-fire plant or SVE/AS treatment systems, and

  • Coal ash when used as road grit.

Potential current exposures to contaminants or hazards from

  • Groundwater contaminants possibly reaching Fort Wainwright or Fairbanks drinking water supplies;

  • On-post surface soil and Chena River surface water/sediment and fish;

  • Radiation from reportedly buried radiologic material;

  • Physical hazards at the post, such as exposed tar, UXO, unlocked utilidors, abandoned structures; and

  • Building hazards associated with lead-based paint and asbestos.

In response to community concerns, ATSDR previously evaluated potential exposure to contaminants in groundwater used for irrigation at off-post property and the possibility that local children might have an increased risk of learning disabilities.

Exposure situations at Fort Wainwright are evaluated in detail in the following discussion and summarized in Table 4. To acquaint the reader with terminology and methods used in this PHA, Appendix B provides a glossary of environmental and health terms presented in the discussion, Appendix C describes comparison values used by ATSDR in screening contaminants for further evaluation, and Appendix D describes the methods ATSDR uses to evaluate whether or not health hazards exist.

IV.B. Public Health Evaluation of Past or Potential Past Exposure Situations

This section focuses on past or potential past exposure to chemicals from Fort Wainwright–historical exposures in which people did contact or had a high probability of contacting site contaminants. These exposures do not currently exist, nor are they expected to occur in the future.

IV.B.1. Drinking Water at the Shannon Park Baptist Church and the Steese Chapel Hall

Two private wells, the Church of Latter Day Saints' Steese Chapel Hall well (referred to as the Steese Chapel Hall well) and Shannon Park Baptist Church wells, are located about ¼ mile west of the Fort Wainwright Birch Hill Tank Farm. These wells were used for drinking water until December 1991, when 1,2-DCA was detected in well water samples. The 1,2-DCA concentration (2.7 ppb) exceeded the ATSDR CV (0.4 ppb) for drinking water for that contaminant. (The details of these results are discussed in Appendix D.) The contaminant concentration in the Shannon Park Baptist Church well also exceeded EPA's drinking water standard for 1,2-DCA (5 ppb) in a sample taken in 1995, but this detection occurred after the well was discontinued for drinking water use. Table 5 summarizes the sampling results for these wells. Fort Wainwright has provided bottled drinking water for the former users of these two wells since September 1998 because of the 1,2-DCA contamination (Nelson 1998, U.S. Army Alaska 1998b).

As part of this public health assessment, ATSDR evaluated the exposure people could have experienced if they drank from the church well in the past. Past exposure to 1,2-DCA in the Shannon Park Baptist Church well water might have occurred during the 7-year period from 1985 through 1991, when the well was used as a source of potable water. Less is known about the use history of the Steese Chapel Hall well, in which 1,2-DCA was detected at levels below the EPA MCL.

After reviewing available environmental data, potential exposure situations, and contaminant toxicology, ATSDR determined that any possible exposures were below levels expected to cause harm to people who drank water drawn from the well in the past. In this evaluation, ATSDR assumed that people who attended the church in the past could have been exposed to 1,2-DCA by drinking water from the church well. ATSDR evaluated possible health effects from this exposure by assuming that members of the congregation drank water containing the highest detected level (5.86 ppb in 1995, after use was discontinued) of 1,2-DCA while attending church over a 7-year period. Adult members were assumed to drink 2 liters (the equivalent of a large soda bottle) and children were assumed to drink 1 liter of water 365 days a year. These assumptions create an extremely protective estimate of exposure that is much higher than an exposure dose for an individual attending church. In all likelihood, people at the church did not consume water as frequently or repeatedly at the highest detected concentration. These estimates, however, allowed ATSDR to safely evaluate the likelihood, if any, that the drinking water contaminants from the church well could harm well users. Appendix D gives more detail on how ATSDR reached this conclusion.The Army is currently taking measures to prevent current and future contamination of groundwater and drinking water supplies.

The Shannon Park Baptist Church well is still used for irrigation. Monitoring conducted after the wells were no longer used for drinking water showed benzene at levels (to 2.2 ppb) above ATSDR's CV yet well below EPA's regulatory standard of 5 ppb and, as previously mentioned, 1,2-DCA at levels above EPA's MCL. In 1999, in response to community members' concerns, ATSDR evaluated potential exposures from irrigation use and found no public health hazards associated with any exposure scenario; the levels of VOCs in the groundwater used for lawn irrigation posed no public health hazard. ATSDR's findings are presented in the 1999 ATSDR health consultation (ATSDR 1999a), and summarized in the "Community Health Concerns" section of this document. Although some contaminants were present in the groundwater used by the churches, there was no exposure to the contaminants that would harm church parishioners or workers; therefore ATSDR categorized this as a no apparent public health concern.

IV.B.2. Releases to Ambient Air

Potential sources of air pollutants from Fort Wainwright operations include particulate matter (PM10) from the coal-fired power plant and VOC emissions from the SVE/AS remediation systems.(1) Other contaminants from site operations include VOCs from aircraft maintenance activities and landfilling operations. Emissions from the coal-fired plant and from the SVE/AS systems area are discussed below.

Coal-Fired Power Plant

The Fort Wainwright coal-fired power plant supplies heat and electricity for the post. The power plant burns approximately 300 tons of coal per day during the summer and up to 1,200 tons per day in the winter. The coal-fired power plant is a little less than 2 miles east of the western boundary of the post. The closest on-post housing is about 0.5 miles west of the power plant. Another on-post housing area is located a little more than 1 mile north of the power plant. There is an off-post housing area a little more than 1 mile northwest of the power plant.

ADEC has twice issued notices to Fort Wainwright (one in 1994 and another in 1996) for air pollution violations (EPA 1999). EPA issued a Notice of Clean Air Act Violation to the coal-fired power plant on March 10, 1999, because the plant was operating without adequate emission controls and functioning monitors (EPA 1999). Also, from the 1960s to 1993, the coal pile used for fuel at the plant was sprayed with waste petroleum fuel products (e.g., diesel, fuel oil, solvents, and lubricants) from tanks, railroad cars, and drums while they were stored at the Coal Storage Yard. The oil was used to increase the British thermal unit content of the coal and ultimately improve the output of the coal fired-power plant (EPA 1996).

No on-post or off-post air monitoring data are available to evaluate the potential public health impact of air emissions from the coal-fired power plant during normal operations or while it was burning coal that had been coated with waste oil. Two ambient air monitors were installed near the power plant and began operating in February 2003. Results indicate Fort Wainwright currently meets National Ambient Air Quality (NAAQ) Standards for sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO) and PM10 (Siftar 2003a; personal communication). ATSDR reviewed general information about coal-fired power plants from a variety of sources to obtain basic information about coal-fired power plant emissions and their potential effect on the local community. ATSDR summarizes its findings in the discussion that follows and presents a more detailed review in Appendix D.

Coal combustion has a variety of byproducts. When these byproducts are released into the air as pollutants, their type and amount depend upon a combination of factors, including the composition of the coal, coal-combustion conditions, and the type and condition of air pollution control equipment. The major constituents of the gases emitted from coal-fired power plants are sulfur dioxide (SO2), nitrogen oxides (NOx), and carbon dioxide (CO2) (DOE 2002). Other elements and compounds also are released, but at much lower concentrations. These include metals, such as mercury and selenium, and particulate matter. It appears that the concentrations of the various metals released are typically small. Therefore, the major public health concern is from the amount of particulate matter released, not the concentrations of the metals. Various polycyclic aromatic hydrocarbons (PAHs) also have been identified in the flue gas of power plants after coal combustion (Katoh 2002). The specific type and amount of PAHs emitted depends largely on the combustion conditions and only slightly on the type of coal burned. The information ATSDR reviewed suggests that properly operating combustion chambers and pollution control equipment can significantly reduce the amount of pollutants (i.e., particulate matter, metals, and PAHs) released from coal-fired power plants.

ATSDR also reviewed available information on the impact of coal-fired emissions on neighboring communities. Some studies indicate that mercury emissions from coal-fired power plants do not necessarily affect local communities but have more of a global effect (Maryland Department of Natural Resources 1999). This information suggests that the emissions are spread over an extremely large area, so a community is exposed to only a small amount of the contaminants emitted from its own coal-fired power plant. In a different study, EPA assessed the inhalation risk of people exposed to certain airborne contaminants (e.g., mercury and arsenic) in their communities. These findings indicate that properly operating local coal-fired power plants do not represent a public health hazard to the surrounding community.

The effects of releases during periods of noncompliance (1994, 1996, and 1999) on people living in surrounding communities are not known with certainty. Air models, such as EPA's SCREEN3 (an approved transport and dispersion screening model), can help to estimate if concentrations in ambient air could be affected by emissions and to identify areas with the highest expected breathing-zone concentrations. Preliminary results from using SCREEN3 to evaluate emissions from the Fort Wainwright coal-fired power plant suggest that under some operating and meteorologic conditions, air pollutant concentrations downwind from the power plant could exceed the National Ambient Air Quality Standards. Though not definitive, this analysis does suggest that, depending on the meteorological and operating conditions, the outdoor air quality in the nearby residential area could be affected by emissions from the power plant, especially when the plant is operating without appropriate pollution control measures. As previously mentioned, the air monitoring stations in place since February 2003 indicate that Fort Wainwright currently meets the NAAQ standards.

Based on the available information, it is not possible to determine with certainty if nearby residents were periodically exposed to contaminants released by the power plant. This review does indicate that periodic exposures to contaminants released from the stack were possible. However, it is not possible to determine whether possible releases from the Fort Wainwright coal-fired power plant were sufficient to cause adverse health effects in the local community without specific information about the type and quantity of contaminants in the air and about the frequency and duration of exposure. The information reviewed suggests that emissions from the power plant would not be expected to adversely affect the health of the local population when the power plant is operating efficiently and properly, using properly functioning, approved pollution control equipment. Fort Wainwright is currently installing air pollution control equipment to remove particulates from the exhaust stream for each of the power plant's boilers (Siftar 2003a; personal communication). ATSDR concludes that while there may have been past exposures to air pollutants; Fort Wainwrights efforts to both reduce and monitor the emissions from the power plant are expected to keep the emissions within state and federal regulatory limits and be protective of public health. Because it is not possible to quantify the potential past exposure to contaminants released from the power plant, ATSDR categorized this as an indeterminate public health hazard.

Soil Vapor Extraction/Air Sparging Systems

Beginning in 1994, SVE/AS systems have been operating on post as part of the soil and groundwater remediation efforts. Most of the contaminants removed by these systems is in gas form. When the systems were originally installed, they were not equipped to capture all the volatilized chemicals. Many of the systems were brought on line in 1997. An emissions inventory shows that Fort Wainwright emitted 54 tons of VOCs in 1997 (CH2M Hill 1998b). Under the currently applicable permits, Fort Wainwright is limited to 40 tons of emissions postwide; 30 tons per year from restoration activities (Siftar 2003b, personal communication).

Emission controls were installed on the SVE/AS systems in 1997 and 1998, bringing VOC emissions back into compliance. Monitoring in 1999 and 2003 indicates that emissions from SVE/AS systems have dropped, and are within the permitted levels (ENSR 2000; Siftar 2003). As long as the SVE/AS systems are operating and the control measures are in place, no public health hazards from these sites are expected. No air monitoring data is available for the period when the emissions were above current permit levels (1997 and 1998). While the potential exposures to these emissions can not be determined, it is expected that the potential exposures would have been below levels that would cause health effects. Because relatively low levels of contaminants were released into the air for only a short time, ATSDR categorized this potential exposure as no apparent public health hazard.

IV.B.3. Coal Ash Applied as Road Grit

Coal ash, produced as a byproduct of coal combustion at the Fort Wainwright power plant, was used as road grit for on-post, ice- and snow-covered roads, for an unspecified period of time until 1992 (Fort Wainwright 1992). Although coal ash is no longer used for this purpose, ATSDR was concerned about possible health hazards to people who once lived in areas where coal-ash road grit was used.

Background Information on Coal Ash and Use at Fort Wainwright

Coal ash is a residue from burning coal in a power plant. Modern power plants typically have four sources of coal ash: bottom ash, fly ash, flue-gas-desulfurization sludge, and fluidized bed combustion waste. Approximately 16% of the coal ash produced by power plants is bottom ash (Kalyoncu 2001). Bottom ash tends to resemble shattered glass and can be abrasive (FLYGT 2003). It ranges in size from dust particles to sand-size grains about 0.375 inches in diameter. The larger particles are essentially nonrespirable. Laboratory tests of road grit conducted by Fort Wainwright indicate that the grit contains relatively minor, varying amounts of the metals arsenic, barium, cadmium, lead, mercury, selenium, and silver.

Potential Health Hazards Associated With Coal Ash

There are no specific environmental data on the concentration of ash in the soil, groundwater, or air following its application to the roads at Fort Wainwright. In the absence of these data and to evaluate potential past exposure, ATSDR gathered information about common concerns associated with coal ash applied to ground surfaces to understand the potential movement of coal ash to soil, groundwater, and ambient air, and its potential to affect public health.

ATSDR considered three potential public health concerns related to the practice of using the coal ash as road grit: (1) potential contamination of soil along the road from metals in the ash and subsequent incidental ingestion of that soil by Fort Wainwright residents, (2) infiltration of contaminants into the groundwater and potential ingestion in drinking water, and (3) inhalation of contaminants generated by vehicular traffic.

As an initial screen, ATSDR compared the concentrations of metals in the ash to CVs for soil. (If the concentrations were below the CVs, the contaminants were far below doses known to produce adverse health effects.)To be protective, ATSDR evaluated the maximum detected concentrations, recognizing that it is highly unlikely in most exposure situations that a person will be continuously exposed to the highest concentration detected over time. ATSDR's findings are summarized below. The assumptions and methodology used in evaluating these exposure scenarios and deriving the conclusions are discussed in more detail in Appendix D.

  • Potential ingestion exposure to ash metals in the soil. ATSDR considered the potential for children playing near treated roadways to inadvertently ingest metals in the coal ash. Metal concentrations in the ash were either below the ATSDR CVs or below levels of health concern.

  • Potential ingestion exposure to ash metals from groundwater contamination. ATSDR considered the potential for metals in the coal ash to infiltrate to the underlying groundwater. Metals do not easily move through soil to the underlying groundwater. Because the metal concentrations measured in the ash are were within the ATSDR CVs for soil, harmful levels of these metals in the groundwater are not expected.

  • Potential inhalation exposure to ash metals released into air. ATSDR considered the potential for people to inhale metals in road grit ash that has become airborne in dust after traffic on the roads. This evaluation was performed using the format described by EPA to estimate the particulate concentrations released from road surfaces as a result of vehicle traffic. In applying this model, ATSDR assumed the most conservative, yet realistic, exposure conditions in deriving exposure estimates. All estimated metal concentrations in the grit were well below the ATSDR CV for inhalation exposure, except for arsenic. ATSDR reviewed the toxicologic literature on arsenic and concluded that short periods of exposure would not lead to adverse health effects.

On the basis of comparisons to screening CVs, ATSDR found no evidence of contaminants in coal ash at levels known to be associated with adverse health effects in soil, groundwater, or air. Furthermore, it is unlikely that a child would actually come in contact with high concentrations of metals in coal ash because (1) after the ash was added to the landscape, the effective concentration of the metals was reduced as the ash mixed with the surrounding soil or was diluted with runoff and (2) children are unlikely to spend unsupervised time along roadsides, where contaminant concentrations are the highest. As a result, children were not likely to consume the quantities of metals that are associated with adverse health effects. Because on-post residents and workers were not exposed to contaminants at levels that could cause health effects, ATSDR categorized this potential exposure pathway as no apparent public health hazard.

IV.C. Public Health Evaluation of Current and Potential Current Exposure Situations

Current or potential current exposure refers to an exposure occurring at the present time. Certain exposure situations pose ongoing concerns that have existed over time from both past and current exposures.

IV.C.1. Area Drinking Water Supplies

ATSDR's evaluation of potential public health hazards associated with groundwater concentrated on (1) identifying drinking water sources for Fort Wainwright and off-post communities, (2) identifying on-post contaminant sources that can affect on-post or off-post water supplies, and (3) assessing whether people could come into contact with harmful levels of contaminants from drinking water. Each of these issues is discussed below.

Drinking Water Supplies for Fort Wainwright and the City of Fairbanks

Groundwater pumped from the Tanana Basin Alluvium Aquifer serves as a primary source of drinking water for Fort Wainwright. Employees and residents are provided with drinking water from Fort Wainwright's own drinking water system. Residents of the city of Fairbanks and the surrounding area obtain drinking water from one of three sources: the Fairbanks municipal system, private wells for residents living beyond the city connections, or a water delivery service. Each of these sources of drinking water is discussed below.

Drinking Water Supplies at Fort Wainwright

Fort Wainwright supplies its own drinking water using wells located on post. Two main drinking water wells, 3559A and 3559B, and a backup well, 3565, supply most of the post with drinking water. Wells 3559A and 3559B are used on an alternating 3-month rotation. Another well at Building 3563 is used as a backup well in the event of pressure loss. All of these wells feed into a common distribution system. Three standby wells (at Buildings 1032, 3405, and 1011) are connected to the distributions when needed (Fort Wainwright Water Treatment Plant 2003). Several other wells that are not connected to the distribution system are used to supply drinking water to certain areas of the post (Dowl/Ogden 1997). These wells include the following:

  • Well 110, which supplies the Birch Hill Ski Lodge, is located in Building 1172 in the northern portion of the post, 1.5 miles east of the Tank Farm Facility.

  • Well 109, which is located in Building 2072, supplies the post's golf course club house. (The golf club also has a separate irrigation well located near former Building 2250.)

  • The wells located in Buildings 5108 and 5110 supply the Range Control area and Range Maintenance, respectively.

  • Well 127, located in Building 5007 within the DRMO, is used to supply drinking water for that area.

Fort Wainwright participates in a wellhead protection plan that recommends ways suppliers can prevent contamination of groundwater supplying the drinking water wells. Fort Wainwright's draft wellhead protection plan identified land around each well to be protected, as well as potential sources of contamination for each supply well. A wellhead protection area (WHPA) is the "surface area from which potential contaminant releases could reach the water source supply"; it is determined by the fixed-radius method, a computation of "a cylinder with a pore volume equal to the volume of the water pumped during a specified period" (USACE-AK 2000).

Each year, Fort Wainwright Public Works reviews and documents the status of each PSC within a WHPA to determine the best management practice for each PSC. The Department of Public Works also informs personnel and their families, through a public education program, about the locations of water supplies and how to minimize potentially hazardous impacts on these supplies. The department also prepares a yearly report on potential impacts to water supplies, based on extensive groundwater monitoring at the site (USACE 2000a). Water-quality monitoring conducted through 2000 has not revealed any impact by these PSCs on the post's drinking water supply (USACE-AK 2000b).

Drinking Water Supplies for the City of Fairbanks and Surroundings

Residents of the city of Fairbanks obtain their drinking water from the municipal water supply, their own private wells, or from a delivered water service. Each of these water supply sources is discussed below.

  • Municipal water. Municipal water for the city of Fairbanks is operated by Utilities Services of Alaska, Inc. This company, created in 1997 from the former Fairbanks Municipal Utilities System, is a private company that has provided administrative oversight to two water providers, Golden Heart Utilities and College Utilities Corporation. The municipal water system is primarily used by city residents living in the eastern portion of Fairbanks and adjacent to the western boundary of Fort Wainwright, including some neighborhoods northwest of the post. Starting in 1971, Golden Heart Utilities began operating four drinking water wells located about 1 to 2 miles west (approximately downgradient) of Fort Wainwright and along the Chena River. These wells are screened about 100 feet bgs. The water system contains two reservoirs with a combined storage capacity of over 6 million gallons of treated water. College Utilities Corporation provided water from three wells also screened 100 feet bgs along the Chena River. In 1999, these wells pumped an average of 1 million gallons per day to 10,000 College Utilities costumers, and a 1-million-gallon capacity water storage tank. Since February 2002, when College Utilities Corporation closed its aging water plant, all municipal users have received drinking water from Golden Heart Utilities.
  • Although the shallow aquifer beneath certain areas of Fort Wainwright is contaminated with substances related to former site activities, no municipal wells have been affected by the on-post contamination. Golden Heart Utilities and College Utility Corporation obtained their water from the uncontaminated portions of the aquifer. These utilities also monitor water from drinking-water-supply wells in accordance with the EPA Safe Drinking Water Act to ensure that municipal drinking water meets safe drinking water standards. This act requires public water suppliers to test their water regularly for harmful contaminants, and it specifies that concentrations of these chemicals must not exceed the chemicals' EPA MCLs. (The MCLs are EPA-established, enforceable drinking water regulations that are protective of public health.) To date, drinking water has been safe to drink (Utility Services of Alaska 2001a, 2001b). Water provided to Fairbank residents is treated to remove iron and manganese, which cause a bad taste and staining. Because of the arctic cold, the entire treatment process and water storage is conducted indoors.

  • Private wells. Some people in the area rely on groundwater from private wells. Private well owners are not required to test their well water for compliance with EPA's safe drinking water standards. Private well use in the area is described below.

    • South and east of Fort Wainwright. More than 70 private drinking water wells are located in a village subdivision southeast of the DRMO yard, with the nearest well 400 feet to the southeast, and upgradient of the site (ENSR 1996). The municipal water system does not extend to these residential areas (Dean 2001). Residential subdivisions adjacent to the eastern boundary, and upgradient of Fort Wainwright, are also beyond municipal service, these residents are provided by water from private wells located in their subdivisions. Utility Services of Alaska, Inc., and the Army are planning to extend water service to the area east of Fort Wainwright in the future (Dean 2001).


    • West of Fort Wainwright. Two nonmilitary residential subdivisions also are located adjacent to Fort Wainwright's western boundary, approximately 1,000 feet southwest of Building 1168 (where soil contamination around a leach well has contaminated the underlying groundwater). Most residences of the subdivisions are connected to municipal water supplies, however, some private wells are in use (U.S. Army Alaska 1996a). Groundwater monitoring indicate that contaminants from this site do not threaten off-post residential wells.
    • The Shannon Park Baptist Church and the Steese Chapel Hall private wells are located about 0.25 mile west of the Fort Wainwright Birch Hill Tank Farm. These wells are no longer used for drinking water since 1,2-DCA was detected in 1991. Concentrations of the contaminant in both wells exceeded the ATSDR CV for drinking water. The concentration in the Shannon Park Baptist wells also exceeded EPA's safe drinking water standard after the well was no longer used for drinking water. Fort Wainwright has provided bottled drinking water for the users of those wells since September 1998 (Nelson 1998). The Shannon Park Baptist Church well is still used for irrigation. ATSDR evaluated potential exposures from irrigation use and found no public health hazards associated with any exposure scenario. These findings are presented in ATSDR's 1999 health consultation (ATSDR 1999a) and summarized in the Community Health Concerns section of this document.

    • FEP Milepost 15.75. An unknown number of private wells are used in a residential area along Laurence Road and Robyn Drive. In 1989, the FEP pipeline rupture at Milepost 15.75 in this area, approximately five miles east-southeast of the main Fort Wainwright cantonment area. Residential private wells exist approximately 200 feet from the source area. The depth of these wells is not known.

  • Delivered water. Some residents of Fairbanks rely on drinking water that is delivered to their residences and stored in tanks on their property. The Pioneer Wells Water Company (Pioneer) in Fairbanks has been providing this service to Fairbanks residents since 1924. The Pioneer wells, located southwest of the leach well at Building 1168 and near Trainer Road in the Hamilton subdivision, were sampled in 1993 and 1994 by ADEC. No VOCs were detected above CVs in either sampling event (Ecology and Environment 1994). The highest concentrations of contaminants were detected in the immediate vicinity of the former leach well–not downgradient or off site.

Source Areas Potentially Affecting Drinking Water Supplies

Several releases and spills at Fort Wainwright have occurred. Most contaminants found at Fort Wainwright (e.g., fuels, solvents, and metals) can be carried in rainwater and snow melt through soil, and even through permafrost and seasonally frozen soil, to the underlying groundwater. Contaminants in the shallow groundwater can migrate from the source area, typically traveling in the direction of regional groundwater flow. (Close to the source, however, contaminants could initially travel anywhere from the north to the southwest for short periods of time before being incorporated into the regional flow pattern.) As a contaminant migrates, its concentration in the groundwater is expected to decrease with increasing distance from the source area.

The presence of contaminants in groundwater does not necessary result in human exposure. People are only exposed to a contaminant, such as those identified in the groundwater beneath the Fort Wainwright site, if they come into contact with the contaminant; for example, through ingesting contaminated drinking water. For this reason, ATSDR was interested foremost in areas in which contaminated groundwater has or could threaten area drinking water supplies.

From this review, ATSDR identified the following drinking water supplies that are possibly vulnerable to site-related groundwater contamination that could expose people to site-related contaminants:

  • Fort Wainwright drinking wells in the vicinity of the Coal Storage Area,

  • Private wells near the FEP spill in city of North Pole,

  • Private wells close to the FEP spill near the northeast corner of Fort Wainwright, and

  • Pioneer wells that are located near the Building 11678 leach well.

Public Health Evaluation of the Groundwater Pathway

ATSDR evaluated potential exposures to site-related contaminants for workers and residents who might use the water systems identified at Fort Wainwright and in Fairbanks as their source of drinking water. On the basis of this evaluation, ATSDR concluded that drinking water drawn from any of these systems has not caused, nor is it expected to cause, harmful health effects. The following discussion provides information about each of the drinking water supply systems, the potentially exposed population, and potential exposure parameters used to reach conclusions.

Fort Wainwright's Drinking Water Supply

Fort Wainwright draws its drinking water supply from wells in the aquifer beneath the site (DOWL/Ogden 1997). Two main on-post supply wells and the backup well (3559A/B and 3565) are located approximately 1,500 to 1,900 feet downgradient of the Coal Storage Yard, an area known to be contaminated with VOCs. The coal storage area falls within WHPA for these wells. To ensure protection of these drinking water wells, the Army continues a semi-annual soil- and groundwater sampling program.

The Army's environmental investigations have included limited sampling of the post's drinking water wells (DOWL/Ogden 1997). Sampling results have included chemical concentrations above ATSDR's CV for some chemicals; these appear to be transient occurrences, and they do not appear to be an indication of contamination at a level of health concern. Results from 1986, indicate that three VOCs, chloroform (72 ppb), bromodichloromethane (2 ppb), and methylene chloride (71 ppb) were in the post drinking water at levels that exceeded their ATSDR CVs. In 1995, arsenic was detected in 5 of the 10 wells at a maximum of 12 ppb, and 1,2-dibromoethane was detected in one well at 0.2 ppb (USACE-AK 1995). The maximum concentration of arsenic in the drinking water wells was slightly above the revised EPA MCL of 10 ppb, but this concentration is not expected to pose long-term health effects to its users.

The post also conducts routine water-quality monitoring procedures according to federal and state requirements. The main supply wells are sampled monthly for total coliform bacteria, annually for nitrate and VOCs, and two consecutive quarters per year for pesticides. The main water supply wells also are tested for metals, typically every 3 years, but Fort Wainwright has received a waiver until 2010, because of a lack of metal detections during previous monitoring events. (The wells at ski lodge, golf course, and range follow the same testing schedule as the main wells for coliform, nitrates, VOCs, and metals. Testing at the DRMO follows a more aggressive schedule, with testing of VOCs and SVOCs each quarter.) Recent tests show that contaminants are below ATSDR's CVs (Irwin 2001). Considering this information, ATSDR concludes that drinking the post water or using it in residences would not be expected to harm its users or increase their risk of adverse health effects, and categorized this as no public health hazard.

Off-Post Private Wells by FEP Milepost 15.75 Pipe Break (the City of North Pole)

The FEP which runs through the northern part of the main cantonment area provided the post with fuel. The underground pipeline was placed in service in 1955, to transport fuel from Haines to Fairbanks. The pipeline was active until July 1992 (HartCrowser 1997c). A pipeline rupture occurred in 1989, at milepost 15.75 in a residential subdivision west of the city of North Pole (at the intersection of Laurance Road and Robyn Drive). About 4,200 gallons of fuel are estimated to have spilled. Approximately 2,400 gallons of fuel were recovered within 2 hours of the spill (Putnam 1989). Each house in this subdivision is believed to have its own private well. The nearest wells that potentially could be impacted by the contaminants are about 200 feet from the source area.

Sampling was not identified for the private wells, but three monitoring wells were installed between the spill location and the private residences. During the OU 3 RI in 1993, benzene (34 ppb) and 1,2-DCA (8 ppb) were detected at levels above their CVs in groundwater monitoring wells for this site. This site does not have a continuing source of contamination, and a SVE/AS system was scheduled to be installed in November 1996 to prevented a contaminant plume from migrating toward the residential area (Ecology and Environment 1994). Another monitoring well (AP-7267) was installed between the pipeline break location and the private drinking water wells. No VOCs were detected in AP-7267 during sampling conducted in 1998 (HartCrowser 1998a). Before installation of the monitoring wells, it was not possible to determine whether contaminants migrated towards the private wells. However, on the basis of the levels detected when the wells were installed and the limited amount of fuel that was released, it is not likely that there was a past exposure to groundwater contaminants at levels exceeding CVs. Because of the decreasing contaminant levels in the monitoring wells (especially AP-7267), it appears that there is no current exposure nor potential future exposure to groundwater contaminants at levels exceeding CVs. Therefore, drinking this water or using it in at this location would not be expected to harm its users or increase their risk of adverse health effects. Because the low levels of contaminants that were measured in the groundwater for a short time are below levels that would cause harm to the residents relying on private groundwater, ATSDR categorized this as no apparent public health hazard.

Off-Post Private Wells by FEP Milepost 2.7 Pipe Break (Near the Northeast Corner)

 

A pipeline break occurred in the 1970s at Milepost 2.7, within a military training area about 1 mile west of and across the Chena River from any residential property (EPA 2003). The source area contains locations that were contaminated by the pipeline break, two truck-fill stands, water separator pits, valve pits, and some pipelines associated with the Birch Hill UST facility. This stretch of pipeline is located in the northeastern corner of the main cantonment area, 2.7 miles east of the tank farm on the southern boundary of the Birch Hill UST site.

Sampling during the 1993 RI of the groundwater beneath the spill area detected VOCs above their CVs, including benzene (471 ppb), ethylbenzene (1,450 ppb), and toluene (964 ppb). Five wells have been installed downgradient to the southwest and southeast of milepost 2.7. The downgradient edge of the plume has not been located, but the contamination appears to have migrated to the southeast along a thaw channel beneath Birch Hill Road.

In 1998, the Army removed 1,500 yds3 of soil from this site. The Army continues to operate a SVE/AS to treat the contaminated excavated soil before local disposal and is still working to achieve acceptable clean-up levels in the excavated, stockpiled soil (U.S. Army Alaska 2002). To ensure that the full extent of contamination has been defined and remediated the Army is evaluating the installation of new monitoring wells at Milepost 2.7 after soil cleanup goals have been reached, and the stockpiled soil has been removed (U.S. Army Alaska 2002c).

Some residential homes are located beyond the northeastern boundary of the base within about 1 mile of this spill area. These residents are not currently connected to the municipal water supply but rely on either private groundwater wells or have their water trucked in and stored in their own storage tank. Because the predominant groundwater flow pattern in this area is towards the southwest, away from any potential private wells, there is no exposure to groundwater contaminants from this site, ATSDR categorized this as no public health hazard.

Off-Post Residences Relying on Trucked Water

The Pioneer wells, located southwest of the leach well at Building 1168 and near Trainer Road, were sampled in 1993 and 1994 by ADEC. No VOCs were detected above CVs in either sampling event (Ecology and Environment 1994). The highest concentrations of contaminants were detected in the immediate vicinity of the former leach well, not downgradient or off site or toward the Pioneer wells. Considering this information, the Pioneer well water is not likely to contain harmful levels of site-related contaminants. Therefore, drinking this water or using it for residential use would not harm its users nor increase their risk of adverse health effects. ATSDR categorized this as no public health hazard.

IV.C.2. Contact with Surface Soil Contamination

Contamination has been detected in surface soil at Fort Wainwright. Sites with surface soil contamination at levels above ATSDR CVs are often located in remote or restricted areas of the post where access is limited, or in industrial areas where children are not going to be playing, nor are adults going to have much soil contact. For example, Buildings 1567, 1599, and 2077, the East and West Sections of the QFS, DRMO, and ROLF are located in industrial areas, not near playgrounds, schools, or other recreational areas that might lead people to contact soil frequently. The Chemical Agent Dump Site, FEP Milepost 2.7, and the Tank Farm Facility/Remedial Area 1A are located away from the main residential areas and are difficult to access. The Tank Farm Facility is also fenced and locked. Moreover, the central Alaskan climate covers the ground surface with snow for a large part of the year (typically October to April), thus reducing the chance of contact (Alaska Climate Research Center 1999). Additionally, a majority of the sites containing contaminants have them at levels below ATSDR CVs. Even if individuals, including post residents (children and adults) engaged in outdoor recreation, military personnel participating in training exercises and hunters in the vast training and maneuver areas away from the main cantonment area, contact low levels of soil contaminants, they are not expected to develop adverse health effects. The frequency and duration of the exposure to these soil contaminants would be below levels necessary to harm public health.

Both the 801 Drum Burial Site and the North Post Site had drums and contaminated soil removed. Post residents use off-road vehicles for recreation at the 801 Drum Burial Site, but exposure to soil contamination from this activity would be limited. The 801 Drum Burial Site is heavily vegetated in the summer, and snow covered in the winter, thus limiting exposure. The contamination at the North Post Site was centered around a burn pit that has since been removed. Institutional controls for the North Post Site also prevent residential housing from expanding into potentially contaminated areas without properly testing the surface soil (ENSR 1996).

ATSDR evaluated potential exposures for on-post workers, post residents, and recreational users to contaminated soil and determined that contaminated soil was inaccessible or that the amount of potential exposure was considered too low to result in adverse health effects. ATSDR concluded that the potential exposures to contaminants measured in surface soil samples are too low to harm to public health. Because the contaminant concentrations in the soil are either very low, or there is little opportunity for exposure to the soil; ATSDR categorized the potential exposure to contaminated soils as no apparent public health hazard.

IV.C.3. Recreational Use of Surface Water Areas

The rivers and certain on-post lakes are used for recreational activities. Of these, the Chena River is widely used by the local community for fishing and boating. Swimming and other water-related recreational activities occur, but are generally limited because of the cold climate throughout much of year.

Relatively low concentrations of site-related VOCs have been detected in samples collected from the Chena River, and those low levels are expected to further dilute before entering the Tanana River. Insufficient sampling data are available to identify if high concentrations of metals exist in the Chena River water. ATSDR evaluated potential exposures to site-related contaminants (based on the available data) for recreational users of the river. Even though some contaminants may exist at levels greater than health-based CVs, individuals who swim or wade while fishing in the river for short periods of time, during certain times of the year, are not at risk of developing health effects. For the type of contaminants detected to cause health problems, people would have to contact the water frequently (daily) and over a long period.In all likelihood, any exposure is likely intermittent and short term and would not have harmful effects. Based on this evaluation, ATSDR determined that the exposure to contaminated surface water or sediment was too low to cause adverse health effects. ATSDR concluded that contaminants in Chena River surface water or sediment are not likely to pose harm to public health. Because of the relatively low concentration of contaminants in the surface water and the very low exposure to the water, ATSDR categorized this as no apparent public health hazard.

IV.C.4. Consumption of Fish From the Chena River

The Chena River is used by the local community for recreational and subsistence fishing. Several edible fish species, including three species of salmon (king, silver, and chum), as well as humpback whitefish, northern pike, and round whitefish inhabit the river. As noted in the "Surface Water and Sediment" section, VOCs and SVOCs have been sporadically detected in Chena River water and sediment samples. The reviewed data indicates that no VOC or SVOC contaminants have been detected frequently enough or at high enough concentrations to suggest that health effects would be expected from consumption of fish caught from this section of the Chena River.

Most contaminants tend to settle to the bottom of the river and collect in sediment. Some contaminants do not decompose easily, so they can remain in the environment for many years after release. Even though contaminant levels in the river's surface water or sediment are relatively low or have been greatly reduced, certain contaminants can persist and accumulate in fish tissue. Fish are exposed to contaminants when they eat smaller fish or sediment containing the contaminants. In this way, larger and older fish can build up high levels of contaminants.

No fish studies have been conducted in the Fort Wainwright area to characterize whether or to what extent site-related contaminants have accumulated in the fish inhabiting local rivers or lakes. The Army completed work on a Chena River Aquatic Assessment in the summer of 2002, which included the collection of macroinvertebrates (such as, insects, and larvae). The study will help determine whether any detrimental effects have occurred to the river environment from off-post areas located upstream and whether the treatment systems are effective in reducing or preventing site contamination from reaching the river (U.S. Army Alaska 2002a).

Currently, ATSDR cannot evaluate if contaminants in the Fort Wainwright section of the Chena River have the potential to accumulate to levels that could cause a public health concern. Surface water and sediment sampling suggests that the levels of VOC and SVOC contaminants measured in the Chena River are not likely to cause health concerns for local fish consumers. Insufficient sampling data is available to identify if metals exist at levels that could indicate a concern for fish consumption. The results of the one sampling event that analyzed metal concentrations in the Chena River water reported that the concentration of some of the metals measured in the surface water sample were above ATSDR's CV for drinking water (arsenic, lead, and selenium). Of the metals detected with measured concentrations above the CV, arsenic was the most elevated. Sampling data is only available from one sampling event. It is not possible to identify if the high concentration of arsenic measured was affected by unusual conditions related to the sampling event or river flow conditions, or if high arsenic concentrations are common for this stretch of the Chena River.

The Chena is not used as a drinking water source, however it is used for fishing. Given the uncertainty in the actual concentrations of metals in the river water, ATSDR was unable to identify if any of the metals exist at levels that could indicate a concern for fish consumption. Of the metals considered in the sampling event, arsenic was the most elevated above its CV. ATSDR reviewed a variety of studies to identify if arsenic could be expected to accumulate in fish tissue to levels that would be hazardous for people who consume significant quantities of fish from the Chena River.

Arsenic may exist in a number of different inorganic or organic forms; the organic forms of arsenic are generally considered to be significantly less toxic than the inorganic forms. Fish tend to accumulate arsenic in the organic form; typically arsenobetaine, a nontoxic arsenic species (Ackley et al, 1999; ATSDR 2000). Norin, et al (1985) reported that the 88 to 95% of the arsenic measured in fish from industrially arsenic polluted brackish and fresh water was of an organic form; the contribution from inorganic arsenic tended to decrease with increasing arsenic concentration. However, the arsenic concentration of the water body was not reported.

The arsenic concentration and speciation can vary for different portions of the fish. Suhendrayatna et al (2001) reported that the total arsenic concentration in the liver of freshwater Tilapia mossambica, exposed to arsenic in the water, was lower than that measured in the muscle tissue and all of the arsenic in the liver was of the organic form. The brain tissue however, had both a higher total concentration of arsenic and a higher fraction of inorganic arsenic compared to the muscle. Again, the arsenic concentration in the water was not reported.

Arsenic does not appear to bioaccumulate significantly in fish tissue under most environmental conditions (Simpson and Lusk 1999; ATSDR 2000; Jack 2003). However, higher arsenic concentrations have been measured in fish from industrially polluted waters than unpolluted waters (ATSDR 2000; Norin et al, 1985). No studies were identified that could be used to estimate the arsenic concentration in fish tissue from arsenic concentrations measured in the surface water or sediment of a water body. Therefore it is not possible to estimate the likely concentration of arsenic in fish from the Chena River.

While it is unlikely that subsistence fish consumers of would be chronically exposed to hazardous amounts of arsenic; as a prudent public health policy it would be best to resample the Chena River surface water. Additional sampling would identify if the single measured arsenic concentration was representative of a single spurious event or representative of a potential exposure for subsistence fish consumers. The Army is scheduled to re-evaluate the sampling needs for the Chena River in 2005; the need for additional arsenic sampling will be considered at that time (Deardorff 2003). ATSDR concurs with this scheduled evaluation and supports additional arsenic sampling for the Chena River in order to identify if the one arsenic sampling event was representative of chronic contamination or just a random occurrence. Because the uncertainties in the measured concentrations of the metals, especially arsenic, ATSDR categorized this potential exposure as an indeterminate public health hazard.

IV.C.5. Lead-Based Paint in On-Post Housing

Children can be exposed to lead if they swallow lead-based paint chips or swallow or breath lead in dust. Compared to adults, a larger amount of swallowed lead will enter the blood of children, putting them at greater risk of lead-related adverse health effects, such as learning disabilities and behavioral problems. The Centers for Disease Control and Prevention (CDC) recommends follow-up examinations, treatment, or both for children with blood lead levels equal to or greater than 10 g/dL. -- Sources: ATSDR 1999c, CDC 2003.A survey of 60 Fort Wainwright residences built before 1960, identified known or suspected hazards from lead-based paints in all of the buildings tested (HartCrowser, 1997). Lead-based paint in residential housing is of concern particularly for young children (see text box). Deteriorated lead-based paint was the most common form of lead hazard at Fort Wainwright; however, lead was identified in the dust in residences and soil around some residential units, presumably from flaking lead-based paint. The greatest hazards are from deteriorating, lead-based paint (peeling, chipping, chalking, cracking or damaged), lead-based paint on surfaces that children can chew or that get lots of wear (e.g., windows, window sills, doors, door frames, stairs, railings, banisters and porches), or home renovation projects involving lead-based paint removal that are not performed using appropriate safety measures (EPA 2001). A questionnaire completed by parents for the 1996 lead-based paint risk assessment (HartCrowser 1997b), suggested that 8% of the children in the surveyed on-post homes were reported to peel or chew on painted surfaces. The survey results also indicated that 12% of the units housed adults who worked in a lead-related industry and many of them washed their work clothes at home. According to information supplied by the parents of children who occupied the surveyed units, less than 10% of the children had been tested for blood lead levels. In addition, those parents were unaware of the test results (HartCrowser 1997b). While these survey results may not be representative of current on-post residents, it does illustrate the need for why a strong lead-based paint program is necessary. Lead-based-paint issues are not unique to Fort Wainwright. More than 80% of all residences built in the United States before 1978 contain some lead-based paint. The older the house, the more likely it is to contain lead-based paint and to have a higher concentration of lead in the paint (CDC 2003).

Lead poisoning is preventable by keeping children from coming into contact with lead (CDC 2003). Measures to identify, evaluate, control, and eliminate areas with lead-based hazards are outlined in Fort Wainwright's Lead-Based Paint Management Plan. Priority is given to areas in which children under the age of 7 years are normally present, such as housing units and day care centers (Fort Wainwright 1999a). When lead-based-paint hazards are identified, the Housing Division notifies occupants that lead-based paint hazards exist in their home and provides residents with information on preventing lead exposure. A child living in a residence with an identified lead hazard is tested for lead exposure, and lead hazards in the home are eliminated or mitigated as residents move out of the affected housing unit.

Lead exposure is typically estimated by tests that measure lead levels in blood. Fort Wainwright's Lead-Based Paint Management Plan (Fort Wainwright 2000) outlines plans for assessing lead exposure risk in children and plans for measuring blood lead levels. The schedule in the Post's Plan calls for screening blood lead levels, as follows:

  • at the 12- month well-baby visit,(2) or

  • as needed for children aged 6 years or under who have not had a previous test for lead, for children whose previous test indicates a blood lead level greater than 10 µg/dL, and for children who have been identified as being at high risk for lead exposure.

Fort Wainwright defines potential lead exposure hazards as 'high risk' based on a child having a sibling or playmate with a confirmed blood lead problem; living or regularly visiting a house, day care center, family child care home, or preschool built before 1960 which has chipping or peeling paint, or recent/ongoing renovation; living near an industrial facility that releases lead; or living with an adult whose job or hobby includes lead exposure (US Army 2000). Lead-based paint was banned in 1978 (Jacobs et al., 2002). Homes built prior to 1978 may contain lead-based paint (EPA 1998).

Fort Wainwright personnel have indicated that to protect the health of on-post children, all on-post residential units are routinely inspected for lead contamination from lead-based paint, and are remediated as necessary. In addition, all new residents receive information from the housing office describing the potential hazards of lead exposure and actions residents can take to reduce their potential exposure (Siftar, 2003b). Because Fort Wainwright has a program established to identify and mitigate exposure to lead-based paint, and a blood lead testing program for children, ATSDR categorized this as a no apparent public health hazard.

IV.C.6. Asbestos in On-Post Housing, Administrative, and Industrial Buildings

Asbestos has been identified in Fort Wainwright housing, administrative buildings, and industrial facilities. During the winter and spring of 1997, approximately 11% of on-post housing units constructed before 1986, and not included in an asbestos remediation effort, were inspected for asbestos. Asbestos fibers in the surface dust and damaged asbestos-containing materials were found in some of the units. The Department of Public Works Environmental Office stated that all removal/abatement actions recommended for the surveyed units have been accomplished and that plans are in place to complete the housing survey and accomplish a survey of workplace areas (HartCrowser1997b). Post personnel stated that, when available, the Housing Division provides all new residents with the results of the asbestos evaluation of their unit.

Until the 1970s, many types of building products and insulation materials used in residences contained asbestos; but most of these products made today do not. The text box below identifies some common building products made with asbestos (American Lung Association 2002).

If the material is in good condition, it will not release asbestos fibers and is not a public health hazard. Asbestos-containing material that has been damaged (i.e., tears, abrasions, or water damage) may release asbestos fibers. Damaged material is more likely to release fibers if it is disturbed or exposed to extreme vibration or air flow. Building materials that could contain asbestos should be checked regularly for signs of wear or damage. Removal of damaged asbestos-containing materials or removal of any type of building material that could contain asbestos should be performed by certified asbestos professionals trained for that type of work. Improper removal of asbestos-containing material can create an asbestos hazard where none previously existed (American Lung Association 2002).

1. Insulation for steam pipes, boilers, and furnace ducts., 2. Resilient floor tiles, the backing on vinyl sheet flooring and floor tile adhesive., 3. Insulating material found around furnaces and wood burning stoves., 4. Door gaskets for furnaces, wood stoves, and coal stoves., 5. Soundproofing or decorative material sprayed on walls and ceilings., 6. Patching and joint compounds for walls and ceilings., 7. Some roofing shingles or siding is made of asbestos cement., 8. Artificial ashes and embers for gas fired fireplaces., 9. Textured paint.

To protect residents at Fort Wainwright against asbestos exposure, the Army has plans to:

  • Inspect all on-post housing units and workplace areas to identify asbestos containing materials.

  • Notify new residents of their residence inspection results, and the procedures to prevent the release of asbestos fibers and report damaged asbestos-containing material.

These measures will help to reduce potential exposure of post workers and residents to asbestos and any associated adverse health effects. Until all on-post housing units and workplace areas have been inspected and remediated as necessary, residents and workers can best protect themselves by following the instructions provided by the Fort Wainwright Department of Public Works to new residents describing the procedures to prevent release of asbestos fibers. Because Fort Wainwright has a program in place to inspect and remediate asbestos hazards, ATSDR categorized this as no apparent public health hazard.

IV.C.7. Radiologic Material Disposal Sites

Two sites in the main cantonment area were investigated by Fort Wainwright and ADEC personnel as possible burial sites for radioactive material. The potential for these sites to contain radioactive material was based predominately on anecdotal information identified by historical record searches and employee interviews. One site reportedly consisted of a buried concrete vault located north of Building 2104 and east of vault 2112, under the runway, identified as the Runway Radioactive Waste Site. This site was never found. The other site reportedly consisted of an above-ground, square concrete bunker having four holes 18 inches in diameter, lined with a vertical concrete drain pipe and sealed on the top with a concrete cover. This site is believed to have been located south of Birch Hill, in a wooded area near the abandoned Birch Hill POL tank farm. It is identified as the Birch Hill Radioactive Waste Site. If radioactive materials were or are buried at these locations, they could potentially release radionuclides to the ground surface and local groundwater resources.

Fort Wainwright and ADEC personnel attempted to identify the location of each of these sites by reviewing historical records and interviewing individuals familiar with the history of Fort Wainwright and the general areas of these two sites. On the basis of their review, a No Further Action (NFA) Recommendation was signed for the Runway Radioactive Waste Site by Fort Wainwright, ADEC, and EPA in June 1992. The Birch Hill Radioactive Waste Site NFA Recommendation was signed by representatives of Fort Wainwright, ADEC, and EPA in early 1993. This section summarizes the background information available for each site and presents ATSDR's evaluation of potential public health hazards of each site.

Runway Radioactive Waste Site

The NFA states that this site reportedly contained low-level radioactive materials (e.g., radio tubes,airplane instruments, and watch dials), apparently encased in a concrete vault and buried under the runway before 1984.A 1958 master plan contains maps showing numerous vaults for lighting and utilities for the runway operation and maintenance. However, no Army records were identified which referenced a radioactive vault in this area, and no individuals were found to have first-hand knowledge of what was buried where. One 1984 map identified this area, but it apparently did not contain enough specific information to identify the vault location.

Field measurements were not conducted in this area to locate potential radiologic sources because, at the time the NFA was signed, no screening techniques existed to identify a potential source inside a concrete vault, buried at an expected depth of 10 feet. The NFA document does state that downgradient groundwater-monitoring wells have been sampled for radioactive isotopes, although the results were not available at the time the NFA was signed.

On the basis of the information provided, ATSDR expects that tiny amounts of a cobalt isotope (Co-60) and radium could be present; resulting, respectively, from the radar tubes and watch dials reportedly buried in the vault. Both cobalt and radium give off gamma radiation. Gamma radiation can travel for long distances in open air; however, it does not travel great distances through dense material. ATSDR expects that no detectable levels of radiation would exist at the soil surface as a result of burial of this material beneath 10 feet of soil and concrete.

While it is possible that future construction projects could result in the unexpected recovery of this vault; Fort Wainwright has procedures in place that require all project managers coordinate all on-base building or digging projects with the base Environmental Office. Project managers who are aware of the potential for finding buried radioactive material at this location will be able to use techniques to protect construction worker and the environment from an unplanned release.

The NFA rationale stated that downgradient groundwater wells could be used to sample for radioactive isotopes, presumably to identify if contaminants were leaching from the vault into the groundwater. On the basis of the information provided, ATSDR expects that a radium isotope (Ra-226) in the groundwater could indicate material from the vault is leaking into the groundwater. In this area of the post, the general direction of groundwater flow is likely toward the northwest. According to the records reviewed by ATSDR, the closest monitoring well located in a downgradient direction (AP-2/AP-5515) is approximately 1,000 feet to the west of this reported burial area. Other wells do exist at greater distances towards the northwest (i.e., AP-5537, approximately 3,500 feet). According to the records reviewed by ATSDR, these wells have not been routinely sampled for radioactive isotopes.

Environmental information indicates that radium tends to adsorb to soil particles, which greatly limits the distance radium can travel in groundwater (ATSDR 1990). Due to radium's low potential for significant transport in groundwater, ATSDR expects that even if the buried vault exists and is leaking small amounts of Ra-226 to the groundwater, on-post drinking water wells would not be adversely affected. Because the radiation source, if it exists, does not represent a radiation hazard to downgradient drinking water wells or to people standing above it, ATSDR categorized this as no public health hazard.

Birch Hill Radioactive Waste Site

The Birch Hill Radioactive Waste Site was apparently discovered and reported by hunters. The only document known to discuss this site is a 1973 article in the Yukon Sentinel, entitled "Army Discovers Old Radioactive Disposal Site." The above -ground bunker was located in a wooded area, surrounded by a fence and signed "Radiation Hazard, Authorized Entrance Only, for Information Contact Post Medical Service." According to interviews with current and former employees, no real radioactive or chemical hazards were found, and the area was cleaned up under the supervision of an explosive ordnance disposal representative from Washington, D.C. Apparently some individuals believe that this above-ground bunker could be the vault reportedly buried under the runway. In that case, the expected radiological materials in the bunker would be Co-60 and radium. However, if the bunker actually contained radiological materials from medical use, ATSDR expects that an isotope of technetium (Tc-99) and/or an isotope of radium (Ra-226) would be the radiological material present in the bunker. Tc-99 is a beta emitter and Ra-226 is a gamma emitter.

On July 8, 1992, the area believed to have been the site of the bunker was surveyed using a conventional Geiger counter and a more sophisticated discriminating scintillometer (Scintrex BGS-1SL Broad Band Gamma Ray Scintillometer). The NFA document reports that neither instrument recorded any readings above background levels and that all treated telephone poles, barbed wire, soil, and a piece of concrete drain pipe were scanned. A NFA Recommendation was signed in early 1993, based on interviews with individuals who stated that the site was cleaned up shortly after it was discovered in the results of the 1992 survey. Given the results of the survey completed in 1992, no health hazards associated with potential radiation releases from the bunker at this site are likely. Because the radioactive material was removed and no radiation was detected during the monitoring, ATSDR categorized this as no public health hazard.

IV.C.8. Potential Physical Hazards

Some people might gain access to the certain parts of the post where they could possibly come in contact with physical hazards. Physical hazards at the post include unlocked utilidors (underground structures providing access for on-base utility maintenance); exposed tar; unexploded ordnance (UXO) at the small arms range; and various physical hazards at the Nike Missile Site and at the maneuver/impact locations (military weapons training ranges). Each of these areas is posted with warning signs advising unauthorized persons to keep out. Persons who abide by these warnings and follow post regulations for site conduct can protect themselves against potential hazards in these areas. ATSDR's evaluation of these potential physical hazards at Fort Wainwright is discussed below.

Utilidors: Potential Asbestos Exposure and Safety Issues

Utilidors are typically small tunnels that form a network running under the residential, administrative, and industrial sections of Fort Wainwright, that carry utilities to buildings. Entrances are near sidewalks around the post, including residential units and playgrounds. Entrances are unlocked, but the doors are heavy, apparently designed in a way so that children will not have the leverage necessary to lift them, but teenagers and adults can. Inside, a utilidor tunnel is lit and has enough room for one adult to comfortably walk and work. A larger utilidor also connects various post buildings (i.e., the headquarters, officer's club, and some officer housing). This larger utilidor has been used in the past as a "walkway connection" between these buildings.

The concern with utilidors is that they contain asbestos as well as physical hazards. (The asbestos in the larger utilidor has been encapsulated.) Anecdotal information suggests children may have occasionally explored and played inside utilidors, putting them at risk of exposure to asbestos and physical hazards. According to the Department of Public Works, there are new entrance lids available which will secure the utilidor from the outside and allow egress from the inside. Use of these new lids will both protect children from access to the ultilidors and allow safe egress of maintenance crews from anywhere in the ulitidor system. As funds are available, the Department is trying to incorporate new lids into new utilidor projects (Fort Wainwright DPW 2001). ATSDR supports measures to replace the existing, unlocked utilidor lids with new lids as quickly as possible, especially for utilidors located near residential and playground areas. Once this is complete, the new lids should eliminate opportunities for unauthorized access and associated hazards.

Tar Sites

Tar Sites and their LocationsFour sites at Fort Wainwright have accumulations of tar on the ground surface (see text box). The tar is believed to be the result of previous disposal practices (USACE 1995); however it is unclear as to when the tar disposal occurred and what, if any, other material also was disposed at these sites. These four tar sites are located near obvious industrial areas or lightly developed areas with access for pedestrian traffic. Each site appears to encompass several thousand square feet of land (Fort Wainwright 1991).

Public access to these tar sites is not restricted by fences and signs are not posted to limit activities in these areas. For some sites, such as the Glass Park tar site, access is restricted by heavy brush. However, other sites, such as the Southgate Road tar site, are easily accessible by pedestrians. Anecdotal information indicates a child did get stuck in one of the tar sites during the early 1990's and was rescued unharmed. During the site visit in July 2001, ATSDR noticed that while it was possible to insert small objects a few inches into the pooled tar; the tar surface remained rigid and fully supported the weight of several adults. It is possible that under very warm and sunny summer conditions the tar surface could become softer and more sticky; under these conditions people walking across the tar site might become stuck.

Some of the tar sites are close to drinking water supplies or the Chena River. Two sites (Southgate Road and Power Plant) are within the WHPA of an on-post drinking water supply well. The other two (Chena River and Glass Park) are located near the banks of the Chena River. The Glass Park tar site, adjacent to Fort Wainwright's western boundary on the bank of the Chena River, is near a short cliff over looking the river. Apparently, tar also is visible at some areas of the cliff face.

In 1992, tar samples were analyzed by the Toxicity Characteristic Leaching Procedure (TCLP). Results of those tests indicated that the tar would not leach contaminants to the underlying groundwater (USACE 1995). On the basis of these results, the Army, EPA and ADEC concluded that there was "no evidence that a potential source of contamination exists at these sites" and signed the No Further Action (NFA) recommendation in 1994, with the comment that future action at these sites should be coordinated with the Solid Waste/Pollution Prevention program of ADEC (USACE 1995). Even though these have been recommended for NFA, ATSDR evaluated possible public contact with or threats to drinking water supplies by tar or other materials at the tar sites.

Background Information on Tar

Tar can be used for either roofing or road-paving construction and is often called by different names, such as asphalt, asphalt cement, bitumen, petroleum roofing tar, pitch, road asphalt, and road tar. In this discussion, the term "tar" will be used to refer to the asphalt-type material. (In actuality, true tars are produced by the distillation of a residue of fractional distillation of crude oil (National Library of Medicine 2003). These "true tars" are not used in construction and are not likely present at the Fort Wainwright tar sites.) There are three different types of asphalt: paving asphalts, roofing asphalts and asphalt-based paint. Most of the asphalt produced in the United States is used for paving and roofing (NIOSH 2000). On the basis of the available information, it appears that the basic composition of the tar is similar for both paving and roofing applications, although the two materials are different and not interchangeable.

Other Materials of Potential Public Health Concern at the Tar Sites

Assuming the existing tar sites were created by disposal of excess roofing tar, other materials might have been disposed at the tar sites following building construction. If this were true, we might expect to see cans of primer, paint, paint thinner, other wall preparations, nails, lumber, asbestos, and dry wall that were disposed of at the tar sites. These other materials could also represent a physical hazard to individuals exploring the area and a potential source of groundwater contamination. However, none of these other building materials have been identified as being discovered in, or near, any of the tar pits. If the tar is surplus road -paving material, it is unlikely that substantial amounts of other building materials would also be present within the tar material. Based on the available information, ATSDR assumed that tar (asphalt cement) is the major material disposed of within the tar sites and,; therefore, it will be the only material considered in the evaluation of impact on drinking water supplies and hazards from contact with site material.

Impacts of Tar Sites to On- or Off-Post Drinking Water Wells

Tar sites are located in the vicinity of drinking water supply wells. For example, two heavily-used post drinking water wells (3559 A/B and 3565) are located approximately 4,500 feet northwest, and in the direction of regional groundwater flow, from the Southgate Road tar site. These wells are also approximately 1,000 feet north of the Power Plant site. (The other tar sites are located further away and/or in upgradient or cross-gradient flow directions from these wells.) Although the dominant groundwater flow direction is likely toward the northwest, ATSDR believes that variations from that direction could occur both temporally and spatially as a result of well pumping.

Samples collected from each of the four main tar sites and analyzed by the TCLP-method in 1992 indicated that the measured concentrations of certain metals in the leachate were well below the TCLP regulatory limits (40CFR261.64). Although the TCLP is a useful test to predict a contaminant's ability to leach from a source under certain conditions, it is limited in its ability to identify contaminant concentrations in the groundwater beneath, and downgradient, of the tar sites. Rather, ATSDR would prefer to evaluate results of groundwater sampling from monitoring wells located immediately down gradient of the tar sites. However, no monitoring wells are located within, or immediately downgradient, of the Power Plant or Southgate tar sites; it is not possible to identify if the tar sites affect the groundwater quality.

The Fort Wainwright Department of Public Works has an active program to test the on-post drinking water supply for compliance with safe drinking water standards. Routine testing shows that the drinking water quality is safe to drink. This information suggests that the post's water supply wells have not been affected by the tar sites. ATSDR therefore concludes that the tar sites are not a public health hazard for the post's drinking water supply.

Contact with Tar by On-Post Residents

Most of the health effects of tar described in the scientific literature are studies of workers exposed to tar, particularly molten tar. The primary immediate hazards for these workers are burns to the skin by direct contact with molten tar and nose and throat irritation from inhalation of fumes from the hot tar; however, there are no reports of long-term health effects (Bergdahl and Jarvholm 2003, Randem et al. 2003a, Randem et al. 2003b, Stucker et al. 2003). After the tar cools, these types of exposures or hazards are no longer possible. Cooled tar, such as that found at Fort Wainwright, is considered to be relatively nontoxic following short-term exposure (US Coast Guard, 2003). Animal studies yield conflicting results about whether long-term dermal contact is likely to cause cancer.

The climate, snow, and heavy cold-weather clothing would prevent direct contact with the material for months at a time. Any exposure during other times of the year is expected to be occasional and short term. Therefore, although the material is easily accessible, people are not expected to have continued, direct contact often enough to cause adverse health effects.

ATSDR noted during site visits that the tar material will stick to certain items, but that people could walk across the tar and touch the tar without getting residual material on shoes or their skin. Given the anecdotal information, it is possible that under certain warm and sunny summer conditions people walking over the tar surface could become stuck. Those tar sites that are easily accessible are also located in open areas near roads. It is likely that if anyone needed assistance they would easily be able to attract attention and help.

ATSDR concludes that contact with the tar material does not present a public health hazard to on-post employees, residents, or visitors. However, under certain conditions the tar sites could represent a physical hazard. ATSDR supports ADEC's NFA request that all future actions involving the tar sites be coordinated with ADEC's Solid Waste/Pollution Prevention Program. Because of the low potential for exposure to contaminants at the tar sites, ATSDR categorized this as no apparent public health hazard. In addition, because the easily accessible sites are also in open areas near public buildings and roads, ATSDR believes there is a low risk safety risk associated with the tar sites.

Unexploded Ordnance Hazards in the 40mm High Explosives Range

Fort Wainwright is an active military installation, where training operations frequently include firing live ordnance. Sites used for ordnance firing are restricted-access areas, not open to the public. However, Fort Wainwright allows hunters, trappers, and fishers (HTFs) to access a great deal of post property, and many of these areas are located near military live-ordnance training areas. Range Control and the military police report that some limited trespassing does occur in parts of the post, leading ATSDR to investigate the potential for HTF or trespassers to inadvertently wander into active small arms training areas or areas containing unexploded ordnance (UXO).

Small-scale arms use occurs during military training operations at the 40 mm high explosive area of the small arms range, located south of the main cantonment area and south of the Richardson Highway. Entrance to this area from Richardson Highway is possible; although it is fenced, the gates are not always closed. This area also can be accessed from a dike along a creek, and is located within a larger area open to hunting.

As part of HTF safety education at the post, Fort Wainwright's military police (MP) require HTFs to sign in and out. During the sign-in procedures, HTF are told which areas they are not to enter. Additionally, Alaska Hunting Regulations and the Alaska Sport Fishing Regulations in the Fort Wainwright area clearly state that it is the sportsman's responsibility to know who the land owner is and to ensure that he has permission to be there. As additional controls to limit unauthorized access, the Army strictly controls training operations at the 40 mm high explosive area and posts "no trespassing" signs along the boundary of the training area that clearly identify the area for military use. (Signs are frequently replaced as hunters use the signs for target practice.) Even if someone does gain access to the testing area, it is unlikely that they would encounter UXO. Ordnance at the small arms range are fired sequentially after the detonation of the previously fired round. Training is stopped if a fired ordnance does not explode; training does not resume until the area is cleared. It is important to note that UXO items will only detonate if tampered with or are otherwise disturbed. To date, there have been no accidents or incidents involving UXO at Fort Wainwright.

ATSDR concludes that limited uncontrolled access by some unauthorized individuals to range areas is possible. Trespassers are at risk for serious physical injury in the event they encounter and tamper with UXO. This area, however, poses no health hazard for the local community or for HTF who follow the requirements of their hunting/fishing license. ATSDR concurs with Fort Wainwright's efforts to educate HTF during the sign-in procedure, to fence in training areas that are continuously off-limits (as appropriate), and to maintain adequate signs on the boundaries of training areas when fencing is not appropriate. Individuals who follow state and Army regulations regarding recreational activities on Fort Wainwright will not be exposed to hazardous materials at this site.

Private (Illegal) Structures in the Maneuver and Impact Areas

More than 30 structures were known to exist on maneuver areas of Fort Wainwright. The structures, ranging from tents to solid walls were typically built and used by HTFs. The majority of the structures are not on impact areas, although some old tree stands/camps remain in the Alpha Impact Area. The Army began to remove the structures in 1998, after public notification of its intent to do so. HTF are allowed on maneuver areas. Legal HTF are required to comply with Alaska state regulations, which clearly state that sportsmen must know who the land owner is and obtain permission prior to entering the land. Methods of contacting the Fort Wainwright MPs to obtain information and permission are clearly available in the state regulations. Copies of the state regulations concerning hunting, trapping, and fishing are available at local stores carrying outdoor equipment and local offices of the state.

Legal HTF are required to check in with Fort Wainwright MPs at entrance and exit of an area, and to remain out of certain training areas and all impact areas. Fort Wainwright regulations and procedures are designed to make HTF aware of the locations they can, and cannot safely enter. Maps are available that designate areas that are off-limits. Copies of the Fort Wainwright regulations are readily available on post. Signs are posted to identify areas that are not to be used for civilian activities.

Signs are used by hunters for target practice and consequently must be replaced often. In addition, moose have learned that impact areas are safe from hunting, so hunters have been known to enter impact areas looking for moose. The Army patrols these areas; trespassers are usually warned, but some have been prosecuted in court.

ATSDR concludes that individuals who hunt, trap, or fish in accordance with state and Fort Wainwright regulations are unlikely to be exposed to military operations or debris. Individuals who violate these regulations by trespassing into restricted areas or utilizing illegal structures place themselves at risk. The contaminants in this area present no health hazard to individuals who follow state and Army regulations regarding recreational activities on Fort Wainwright.

Nike Missile Sites in the Yukon Maneuver Area

Two old Nike Missile Sites are located in the Yukon Maneuver Area. The Army has demolished the buildings on those sites and is currently removing the debris (Siftar 2003). The major concern is for the physical hazards presented by the open holes and construction debris containing lead and asbestos. These sites are in an area used by troops for training, and by hunters, trappers, and hikers.

These sites could present a physical hazard for troops, hunters, trapper, hikers, or campers who attempt to use this site for shelter. These sites are signed as hazardous and advise people to keep out. The signs are frequently replaced because they are used for target practice. The Army Corps of Engineers recently announced a plan to remove building materials attached to the concrete structures and ensure that the surrounding ground is free of all contamination. The bare concrete shell of the building will remain. Completion of the project is planned for the summer of 2003, and will include both the B and C Battery sites (Fort Wainwright DPW 2003). Contaminants in this area present no health hazard to individuals who follow state and Army regulations regarding recreational activities on Fort Wainwright.

IV.C.9. Back Flow of Non-Potable Water to On-Post Drinking Water System

Backflow of non-potable water or contaminated water into the Fort Wainwright drinking water system was identified as a potential health concern. Backflow occurs when clean, potable water flowing from the treatment plant toward the end user suddenly changes direction in the transmission pipe. Common causes of backflow are sudden losses of pressure in the water main resulting from a pipe break or a large draw of the municipal water supply (i.e., fire-fighting or testing a fire hydrant). In such cases, the end user experiences a sudden drop in water pressure at the tap and might observe air flowing out of the faucet. If the faucet is both open and connected to a non-potable water source when a backflow condition occurs, non-potable water may be drawn into the potable water system, for example, when a garden hose is inserted directly into the car radiator while the radiator is being filled, or the garden hose is connected to a sprayer to apply pesticide or fertilizer to outdoor plants.

Backflow is not a unique problem to Fort Wainwright, and it is a potential problem for any potable water system. A review of the literature on back-flow conditions indicates that back-flows have been known to contaminate potable water supplied to individual residences and to entire neighborhoods. Case histories of adverse health effects stemming from backflow are documented in a variety of resources. It appears that the vast majority of backflow incidents were identified and corrected before drinking water users were adversely affected. However, a number of instances are documented in which users became ill after drinking public water that became contaminated by unchecked backflow.

The Safe Drinking Water Act of 1974, established national standards for safe drinking water. State governments are responsible for the enforcement of the standards, and the water supplier is responsible for compliance with all provisions of the act. This includes delivery of safe drinking water to the customer without quality being compromised by the distribution system. However, the water supplier is not held responsible for contamination caused by the customer (EPA 1989). Advise for the development of a local program to control cross-connections and prevent backflow are contained in EPA's Cross-Connection Control Manual (EPA 1989). State and local environmental departments and plumbing codes also provide guidance and direction for water suppliers to identify and correct potential back-flow problems. Fort Wainwright public works personnel have identified vulnerable areas on post and installed prevention devices for back-flow and cross-connection at those locations to protect the safety of the public drinking water supply (Fort Wainwright DPW 2003). Because Fort Wainwright personnel are aware of the possible consequences of backflow and cross-connections conditions and have a program to mitigate those conditions by installing measures to prevent back-flow and cross-connections hazards, ATSDR categorized this as a no apparent public health hazard.


1 Fort Wainwright conducts controlled open burning of land to accomplish natural resources management objectives and remove ignitable material that could cause wildfires. Through this strategy, the military burns about 5,000 acres of land annually at Fort Wainwright. Each year, about 1,600 tons of PM10 associated with the open burns are released into the environment (ADEC 1997).
2 CDC has recommended that physicians evaluate potential lead exposure to children at 9 to 12 months of age and again at about 24 months of age, when blood lead levels peak (American Academy of Pediatrics 1998).

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